1. Field of the Invention
The present invention generally relates to devices that use electrostatic charging, such as an electrostatic sprayer for spraying liquid chemicals, paint, etc. charged with static electricity. More specifically, the present invention relates to a power supply apparatus that supplies high voltage DC (direct current) pulses to a charging electrode, and to a method for supplying power for electrostatic charging.
2. Description of the Related Art
As is known in the art, a typical electrostatic sprayer has a spray nozzle including, for example, a high-potential annular electrode disposed downstream thereof. Using the charging electrode, this conventional electrostatic sprayer electrostatically charges liquids such as chemicals as they are sprayed. The charged, sprayed chemicals adhere well to agricultural crops and the like, and provide the improved effectiveness of bactericide, insecticide, etc.
The typical electrostatic sprayer is generally used in the field, and for this purpose employs a portable battery as a power supply for the sprayer. In operation, a DC (direct current) voltage of this battery is boosted, and is then continuously applied to the annular electrode serving as a charging electrode positioned in the vicinity of the spray nozzle.
However, the typical electrostatic sprayer suffers from several drawbacks. For instance, the typical electrostatic sprayer requires a large battery and includes complicated, expensive electric circuits and devices to boost a battery voltage. In addition, a constant high voltage direct current must be continuously supplied to the electrode, which places a high load on the battery and drains the battery charge quickly. Thus, frequent replacement or recharging of the large battery is required. Further, the heavy weight of the battery makes a handheld or shoulder-type electrostatic sprayer bulky and less maneuverable. In the end, the heavy weight exhausts the operator and renders application procedures less efficient overall.
In light of the foregoing problems, the present invention provides a power supply apparatus for electrostatic charging which is suitable for use in a handheld device that uses electrostatic charging, such as an electrostatic sprayer or similar device. The power supply apparatus produces a pulsed DC high voltage, thereby remarkably reducing a load on the power supply. Further, to operate, for example, a pump in the sprayer, the power supply apparatus uses a compact and lightweight power generator system, such as power generator systems of an igniter for an internal combustion engine. As a result, the present invention uses a small battery and, thus, eliminates cumbersome operations such as the replacement and recharging of a large battery. In addition, the present invention reduces the burden on a user and makes spraying more efficient.
In one aspect of the present invention, a power supply apparatus for electrostatic charging According to the present invention supplies high voltage DC pulses to a charging electrode.
In another aspect, a power supply apparatus for electrostatic charging According to the present invention includes a rotor having a magnet and magnetic poles, a booster facing the rotor, for inducing high voltage AC (alternating current) pulses during rotation of the rotor, and a rectifier for rectifying the high voltage AC pulses induced by the booster to high voltage DC pulses and for supplying the high voltage DC pulses to a charging electrode. With these features, the power supply apparatus of the present invention provides a compact and lightweight power generator system that eliminates the need for a large battery and the associated cumbersome replacement and recharging operations. In addition, the present invention reduces the physical burden on the operator and improves work efficiency.
According to a preferred embodiment of the present invention, the rectifier comprises a high voltage diode or diodes, for the half-wave or full-wave rectifying of the high voltage AC pulses induced by the booster. The high voltage diode may be used to convert high voltage AC pulses to high voltage DC pulses, enabling the resulting high voltage DC to be supplied to the charging electrode in a stable manner.
According to a preferred embodiment of the present invention, the rotor is driven by an internal combustion engine. As such, the rotor of the power supply apparatus faces an ignition coil assembly of an igniter of the internal combustion engine. As the rotor turns and the magnet and magnetic poles pass the ignition coil assembly, the ignition coil assembly generates high voltage pulses and supplies the pulses to an ignition plug of the internal combustion engine. Thus, conventional internal combustion engines can be easily adapted to operate the power supply apparatus of the present invention. For example, in an internal combustion engine that drives a liquid chemical pump, the igniter rotor of the engine may be conveniently used to supply a predetermined power to a charging electrode.
Therefore, the power supply apparatus of the present invention, using a pulsed high voltage, remarkably reduces consumption of electric power as compared to a conventional constant voltage power supply.
Accordingly, an object of the present invention is to provide a compact and lightweight power supply apparatus for handheld devices that use electrostatic charging, such as portable electrostatic chemical sprayers.
Another object of the present invention is to provide an electrostatic charging power supply apparatus that can be driven by an internal combustion engine.
Another object of the present invention is to provide a power supply apparatus that supplies high voltage DC pulses to a charging electrode.
These and other objects of the present invention are described in detail in the detailed description of the invention, the appended drawings, and the attached claims.